Cylindrical Antenna System for Cell Fixation and Coverage Extension in HAPS

High-altitude platform stations (HAPS) have attracted a great deal of attention as a promising candidate for the coverage extension for 6G. However, the coverage achieved by the planar array is limited to a circular area with a radius around tens of kilometers. On the other hand, for a multi-cell configuration in HAPS, frequent switches among coverage areas due to the platform movement is another problem that needs to be solved. In this paper, we proposed a cylindrical multiple input multiple output(MIMO) system for achieving ultrawide coverage and cell fixation in HAPS. In a case where an area with a radius of 50 km is considered, the simulated results show that the proposed system improves signal-to-interference plus-noise ratio by about 1dB at the boundary of the area in comparison to the conventional massive MIMO(mMIMO) using the planar array. In addition, the proposed antenna system can maintain stable coverage in a multicell configuration.